Urea Hydrolysis Feed Rate Control for Ammonia Generation
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Solution Overview
Problem
Existing methods for producing ammonia from urea in industrial processes face challenges in maintaining a consistent ammonia generation rate due to variations in water concentration in the urea solution, leading to fluctuations in ammonia production, which affects the removal of nitrogen oxides from combustion gas streams.
Innovation Solution
A method that involves feeding an aqueous urea-containing solution at a rate matching the external demand for ammonia, using a fluid-tight enclosure or shell and tube heat exchanger with back pressure control to maintain a constant urea and water ratio, ensuring consistent ammonia production, and incorporating a heat transfer medium to hydrolyze the solution, thereby maintaining constant temperature and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the urea solution level in the reactor is kept essentially constant by a fluid level detector governing the pumping rate, then the reactor operates with stable liquid level, but the water concentration in the urea solution varies causing fluctuation in ammonia generation rate
Solution Approach 1:
The patent changes the control parameter from liquid level (prior art) to aqueous urea-containing solution feed rate. By directly controlling the feed rate to match ammonia demand rather than maintaining constant level, the system ensures consistent water concentration and ammonia generation rate proportional to demand
Solution Approach 2:
The patent implements feedback control by linking the urea solution feed rate to the ammonia demand signal from the detection system. The feed rate is dynamically adjusted based on real-time ammonia demand, creating a closed-loop control system that maintains consistent water concentration and ammonia generation rate
2Ease of operation
If the urea solution feed rate is independent of ammonia demand while maintaining constant solution level, then the reactor maintains stable operation, but the ammonia generation rate fluctuates due to varying water concentration
Solution Approach 1:
The patent connects the urea solution feed rate to the ammonia demand signal, creating a feedback-controlled system where the feed rate automatically adjusts to match demand. This ensures ammonia generation rate is directly proportional to demand while maintaining consistent water concentration
Solution Approach 2:
The patent changes the controlled parameter from constant liquid level to demand-matched feed rate. This parameter change allows the system to maintain both operational simplicity and precise control over ammonia generation rate by directly linking feed rate to demand signal
3Productivity
If water is lost as steam in the ammonia going to the combustion gas stream while being a reactant in urea hydrolysis, then the hydrolysis reaction proceeds, but the water concentration in the urea solution varies affecting ammonia generation rate
Solution Approach 1:
The patent changes the control approach from maintaining constant liquid level to controlling feed rate based on ammonia demand. This ensures that water is supplied at the correct rate to match its consumption in the reaction and steam loss, maintaining consistent water concentration
Solution Approach 2:
The patent implements feedback control by linking the urea solution feed rate to the ammonia demand signal. This dynamic adjustment ensures water concentration remains consistent by matching water supply rate to the combined requirements of hydrolysis reaction and steam loss
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in a more responsive, cost-effective, and compact process for producing ammonia, suitable for smaller installations, with improved mixing and reduced risk of condensation and corrosion, effectively addressing the fluctuations in ammonia demand.
Implementation Method 1
wherein a fluid heat transfer medium is present on the exterior of said fluid-tight enclosure to transfer heat to the aqueous urea-containing solution within the enclosure to hydrolyze the solution
Implementation Method 2
to hydrolyze the solution and convert the urea-containing solution to an ammonia gaseous product
Implementation Method 3
the pressure within said fluid-tight enclosure being maintained by back pressure control to ensure that the ratio of urea and water is maintained independent of the ammonia generation rate
Implementation Method 4
convert the urea-containing solution to an ammonia gaseous product comprising ammonia, carbon dioxide and water vapor
Data Source
AI summary
Methods and systems for producing a pressurized ammonia-containing gas stream from aqueous urea. The method comprising pumping an aqueous urea-containing solution to a fluid-tight enclosure at a rate to match the external demand for ammonia-gas, wherein a fluid heat transfer medium is applied to the exterior of the fluid-tight enclosure to transfer heat to the aqueous urea-containing solution sufficient to hydrolyze the solution to an ammonia gaseous product. The systems comprise means for carrying out the methods.